Too artificial, and there's still an initiative to vote.
Perhaps if casting a vote would cost you something.
Money, XP, a pound of flesh, or something. Then only posts
you really care about you would vote on.
I'd wager virtually nobody would vote. The only exception being if the benefits of receiving a vote outweighed the costs of casting it, in which case small groups would agree to upvote eachother's posts. You'd also have more problems with multiple account sign-ups just to upvote nodes.
If you want to make vote's more valuable, simply decrease the supply, then most people would use them more carefully.
Or you could just get rid of the whole silly system. Or make XP private. Or forget about the whole thing ;-)